I've heard supposedly that they add certain fruits and such to the mulch they use when growing the grapes to add different flavours. Maybe that isn't true, or perhaps they believed it worked but it was really part of the fermentation process that created the flavours.

I briefly worked for a french restaurant specializing in french wines. They had a dedicated wine expert who was hired to explain the flavors in wines. While I don't remember everything they taught us, I do remember the basics.

The type of grape has the biggest influence. The most important characteristic of the grape is the thickness of the skin which determines how much tannin is in the grape, which determines how much sweetness or alcohol can be obtained.

The second major influence is the growing conditions, in particular the grape's exposure to sunlight. Does it have consistent hot sun on it, or is it in shade, or does it have inconsistent sunlight, etc..all this has a major effect on how the grape matures and tastes. This is why wines in similar regions may taste similarly..for example in Loire valley, Bordeux, Rhone, or in cali you have Napa valley etc. Depending on the type of grape, it is better grown in different regions.

Another influence is the local terroir...this just means all the other growing conditions. The minerals in the soil (eg, is there bedrock right underneath, limestone, etc) or is there an apple orchard neardby...some places will plant apple trees next to their grapes just so that the apples rot and fall in the soil and hopefully influence the flavor of the grapes. How much difference does this actually make? I do not know

Actually there may be a much simpler explanation (at least for the dominant flavor). It comes from the substrate you are fermenting. One time in my college biochem lab, there were plastic gallon containers all bubbling CO2 into flasks on my bench. Each container had a unique label; strawberry, watermelon, peach, cranberry, banana. Each fruit was being fermented into wine.

I briefly worked for a french restaurant specializing in french wines. They had a dedicated wine expert who was hired to explain the flavors in wines. While I don't remember everything they taught us, I do remember the basics.

junglebeast gives an excellent summary of many of the dominant factors.

I'll just add another one I can think of that I don't think he got to... the container that the wine is fermented in, as well as the length of fermentation in that container. Some people really like "oak" and different types can give different flavor hints or tones... from decidedly woody or earthy, to astringent or tannic, to spicy (like cinnamon, clove, etc.). I found this rather neat http://www.worldcooperage.com/default.aspx" [Broken] that sells different oak barrels.

You know because of this, except most of the French people in strict France I have met, everyone calls me pussy cat. Because I don't smoke or can stand the smoke, and I don't drink at all.
Once I met an European woman and she was surprised when I said I didn't drink beer, then she slowly turned away thinking I am a gay. But I think I am going to be friends with anyone who mostly are like me. "No drink, no smoke, no insults on friends, must talk gently, and above ALL must respect others'kindness and must understand how to sympathize with people around". That's my friends!

I doubt they think you are gay. I have no idea why anyone would think homosexuals are teetotalers. They may think you are 'uptight' or perhaps overly religious. There are alot of people who do not drink or smoke that will lecture or look down upon others who do. That is not to say you would do such a thing but some people may think that you would.

If you've ever had the chance to taste wine grape juice before it's been fermented, you know it doesn't taste like finished wine. It tastes like, well, grape juice. So where do all these fruit, spice and other flavors come from? (Do winemakers put them in?) Can they actually add different flavors to make wine taste a certain way? Well, the answer is yes, and no.

First, let's look at fruit flavors in wine. If winemakers don't add other fruits to wine -- and they don't -- then where do these fruit flavors come from? According to Terrance Leighton, molecular biologist at the University of California at Davis, "A wine's flavor, character and aroma are locked up in the grape, and it's the yeast (through fermentation) that activates -- unlocks -- these characteristics."

A wine grape is a unique fruit in that it contains natural chemical compounds that are also found in other fruits and vegetables. Fermentation, a simple chemical reaction, releases these compounds, and so we smell and taste these same aromas and flavors in the finished wine. For example, the strong black pepper aroma and flavor of California zinfandel (red, of course) comes from the same compound that gives black pepper its spicy kick. And the tangy apple flavor found in most chardonnays comes primarily from malic acid, the tart acid found in apples.